Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain MD Helicopters, LLC (MDHI) Model 369D, 369E, 369F, 369FF, 369H, and 500N helicopters. This proposed AD was prompted by a report of mechanical damage to the main transmission drive shaft coupling (coupling). This proposed AD would require a one-time visual inspection of the couplings for cracks of the splines and, depending on the results, replacement of the couplings. The FAA is proposing this AD to address the unsafe condition on these products.